It probably has to do more of the mental aspect when it comes to gambling and being competitive in general. The more effort you give and strategize to a game, the more you will be affected when you lose. In your case, you get to enjoy your winnings because its either unexpected or you didn't really spend effort or time to make a precise decision on who to bet on. In result, your unexpected winnings would seem effortless for you and you feel more lucky than normal.
Even the strategies don't play out more than ones. A gambler might develop a strategy and gets lucky with it the first time and if the gamer decides to try the same strategy again on a different game he losses out straight. It's still safer not to take gambling as an occupation so that if by chance luck shines on an individual he goes home rejoicing else he wouldn't be affect psychologically because losses in gambling can trigger emotional trauma
It's up to you if you believe you can't be consistent in gambling on the winning side, then never thought of considering it as a source of income as it will never work, what will work is, you'll hard to earn money only to lose money in gambling. It's true that there are people who make a living in gambling, but only a few of them, you are lucky if you have the skills and part of the few, but if not, there's still a way to enjoy gambling and that is by considering it as entertainment only.